Relationship of left atrial size to obstructive sleep apnea severity in end-stage renal disease

Sex-based differences in obstructive sleep apnea and atrial fibrillation: Implication of atrial fibrillation burden

Background

Obstructive sleep apnea (OSA) is a risk factor for atrial fibrillation (AF); however, it is unclear whether AF increases the risk of OSA. Furthermore, sex differences among patients with both AF and OSA remain unclear. We aimed to determine the association between an increased AF burden and OSA and investigate the differences in clinical characteristics between women and men with AF and OSA.

Methods

This was a descriptive, cross-sectional analysis from a prospective cohort study. Patients with non-valvular AF were recruited from the cardiac electrophysiology clinic of a tertiary center; they underwent a home sleep apnea test and 14-day ambulatory electrocardiography. Moderate-to-severe OSA was defined as an apnea-hypopnea index of ≥15.

Results

Of 320 patients with AF, 53.4% had moderate-to-severe OSA, and the mean body mass index (BMI) was 25.6 kg/m2. Less women (38.2%) had moderate-to-severe OSA than men (59.3%) (p < 0.001). In the multivariate analysis, age, being a man, and BMI were significantly associated with moderate-to-severe OSA. AF burden was associated with moderate-to-severe OSA only in men (odds ratio: 1.008; 95% confidence interval: 1.001-1.014). Women and men with OSA had similar BMI (p = 0.526) and OSA severity (p = 0.754), but women were older than men (70.1 ± 1.3 vs. 63.1 ± 0.9 years, p < 0.001). Women with moderate-to-severe OSA had a lower AF burden than men did (27.6 ± 7.1 vs. 49.5 ± 3.9%, p = 0.009).

Conclusions

AF burden is a sex-specific risk factor for OSA and is limited to men. In contrast, women with both AF and OSA have a lower AF burden than men, despite being older and having similar OSA severity and body habitus. Thus, AF may develop later in women with OSA than in men.

Sleep Apnea and Cardiovascular Risk in Patients with Prediabetes and Type 2 Diabetes

Obstructive sleep apnea (OSA) is a common but largely undiagnosed clinical condition, which is turning into a serious public health issue. Of note is that its prevalence is gradually increasing in parallel with the obesity and type 2 diabetes mellitus (T2DM) epidemics. The aim of this article is to comprehensively review the literature in order to evaluate the cardiovascular (CV) risk among patients with OSA and prediabetes or T2DM. OSA seems to be an independent risk factor for the development as well as the progression of T2DM, whereas it is associated with T2DM-related macrovascular and microvascular complications. OSA may also act as a potential risk factor for the presentation and development of CV disease, such as hypertension, coronary artery disease, heart failure, pulmonary hypertension, atrial fibrillation and other cardiac arrythmias, as well as stroke. OSA and T2DM also share common pathophysiological mechanisms leading to atherosclerosis. Considering that the coexistence of OSA and T2DM is an independent and cumulative risk factor for CV mortality, more so than the two diseases separately, clinicians and healthcare professionals should be aware of and screen for OSA in patients with T2DM. Notably, targeted therapy for both conditions seems to substantially improve CV prognosis.

The Impact of Intermittent Hypoxemia on Left Atrial Remodeling in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a significant risk factor for left atrial (LA) remodeling. Intermittent hypoxemia occurs during the sleep cycle in patients with OSAS and plays a crucial role in cardiovascular pathologies such as stroke, arrhythmia, and coronary artery disease. However, there is very little information about the role of intermittent hypoxemia in LA remodeling in patients with OSAS. In total, 154 patients with sleep-related breathing disorders (SRBD) were prospectively recruited for this study. All enrolled SRBD patients underwent polysomnography and echocardiography. Significant OSAS was defined as an oxygen desaturation index (ODI) of ≥10 per hour. Intermittent hypoxia/reoxygenation (IHR) stimulation was used to test the effect of hypoxia on the viability, reactive oxygen species, apoptosis, and inflammation-associated cytokine expression in the HL-1 cell line. To investigate the effect of patients’ exosomes on HIF-1 and inflammation-associated cytokine expression, as well as the relationship between ODI and their expression, exosomes were purified from the plasma of 95 patients with SRBD and incubated in HL-1 cells. The LA size was larger in patients with significant OSAS than in those without. There was a significant association between ODI, lowest SpO2, mean SpO2, and LA size (all p < 0.05) but not between the apnea–hypopnea index and LA size. IHR condition caused increased LDH activity, reactive oxygen species (ROS) levels, and apoptosis in HL-1 cells and decreased cellular viability (all p < 0.05). The expression of HIF-1α, TNF-α, IL-6, and TGF-β increased in the IHR condition compared with the control (all p < 0.05). The expression of HIF-1α, IL-1β, and IL-6 increased in the HL-1 cells incubated with exosomes from those patients with significant OSAS than those without (all p < 0.05). There was a significantly positive correlation between ODI and the expression of HIF-1α, TNF-α, IL-1β, IL-6, and TGF-β; a significantly negative correlation between mean SpO2 and IL-6 and TGF-β; and a significantly negative correlation between the lowest SpO2 and HIF-1α (all p < 0.05). In conclusion, intermittent hypoxemia was strongly associated with LA remodeling, which might be through increased ROS levels, LDH activity, apoptosis, and the expression of HIF-1α and inflammation-associated cytokines.

Is kidney a new organ target in patients with obstructive sleep apnea? Research priorities in a rapidly evolving field

The bidirectional relationship between sleep disordered breathing and chronic kidney disease (CKD) has recently gained a lot of interest. Several lines of evidence suggest the high prevalence of coexistent obstructive sleep apnea (OSA) in patients with CKD and end-stage renal disease (ESRD). In addition, OSA seems to result in loss of kidney function in some patients, especially in those with cardio-metabolic comorbidities. Treatment of CKD/ESRD and OSA can alter the natural history of each other; still better phenotyping with selection of appropriate treatment approaches is urgently needed. The aim of this narrative review is to provide an update of recent studies on epidemiological associations, pathophysiological interactions, and management of patients with OSA and CKD or ESRD.

Obstructive sleep apnea and cardiovascular disease, a story of confounders!

Obstructive sleep apnea (OSA) syndrome is increasingly common among middle aged and older adults and is frequently linked to most cardiovascular diseases (CVD). Sleep-disordered breathing and CVD share a number of common risk factors and comorbid conditions including obesity, male gender, advancing age, metabolic syndrome, and hypertension. OSA appears to be associated with worsened CVD outcomes, sleep-related symptoms, quality of life, and risk of motor vehicle accidents. Demonstrating a cause-and-effect relationship between CVD and OSA has been challenging due to shared comorbidities. Strong evidence demonstrating clinically significant benefit for OSA treatments on OSA-related CVD outcomes are limited. In this review, we evaluate potential pathophysiologic mechanisms that link OSA to CVD and focus on specific treatments for OSA, including positive airway pressure (PAP), dental devices, and surgeries with regard to OSA-related CVD outcomes.

Fluid Redistribution in Sleep Apnea: Therapeutic Implications in Edematous States

Sleep apnea (SA), a condition associated with increased cardiovascular risk, has been traditionally associated with obesity and aging. However, in patients with fluid-retaining states, such as congestive heart failure and end-stage renal disease, both prevalence and severity of SA are increased. Recently, fluid shift has been recognized to play an important role in the pathophysiology of SA, since the fluid retained in the legs during the day shifts rostrally while recumbent, leading to edema of upper airways. Such simple physics, observed even in healthy individuals, has great impact in patients with fluid overload. Correction of the excess fluid volume has risen as a potential target therapy to improve SA, by attenuation of nocturnal fluid shift. Such strategy has gained special attention, since the standard treatment for SA, the positive airway pressure, has low compliance rates among its users and has failed to reduce cardiovascular outcomes. This review focuses on the pathophysiology of edema and fluid shift, and summarizes the most relevant findings of studies that investigated the impact of treating volume overload on SA. We aim to expand horizons in the treatment of SA by calling attention to a potentially reversible condition, which is commonly underestimated in clinical practice.

Association between left atrial enlargement and obstructive sleep apnea in a general population of 71-year-old men

Left atrial enlargement has been shown to be associated with obstructive sleep apnea in patients with coronary artery disease and in sleep clinic cohorts. However, data from the general population are limited. The aim of this study was to investigate whether there is an association between obstructive sleep apnea and left atrial enlargement in a random sample from a general population of 71-year-old men. As part of the longitudinal population study The Study of Men Born in 1943, we analysed cross-sectional data for 411 men, all 71 years old, who had participated in an overnight home sleep study and a standardized echocardiographic examination. Of the 411 men, 29.4% had moderate to severe obstructive sleep apnea [apnea-hypopnea index score of ≥15 (n = 121)]. These participants showed a significantly higher frequency of systolic heart failure, hypertension, overweight, had greater waist circumference as well as higher left atrial areas compared with men with no or mild obstructive sleep apnea (23.7 ± 5.5 cm² versus 21.6 ± 4.5 cm² , P < 0.001). In a linear regression analysis, obstructive sleep apnea was significantly associated with left atrial enlargement after adjusting for overweight, atrial fibrillation, heart failure with reduced ejection fraction, hypertension and mitral regurgitation. Compared with individuals without obstructive sleep apnea, the mean left atrial area was 1.7 ± 1.5 cm² larger in men with severe obstructive sleep apnea (P < 0.05) and 1.3 ± 1.1 cm² larger among men with moderate obstructive sleep apnea (P < 0.05). In this cross-sectional study of 71-year-old men from the general population, left atrial area was independently associated with prevalence and severity of obstructive sleep apnea.

Hypervolemia and Sleep Apnea in Kidney Disease

In end-stage renal disease (ESRD) and heart failure, conditions characterized by fluid overload, both obstructive sleep apnea (OSA) and central sleep apnea (CSA) are highly prevalent. This observation suggests that fluid overload may be a unifying mechanism in the pathogenesis of both OSA and CSA in these conditions. An overnight rostral fluid shift from the legs to the neck and lungs has been shown to contribute to the pathogenesis of OSA and CSA, respectively, in various different patient populations. This article reviews the evidence that supports a role for fluid overload and overnight fluid shift in the pathogenesis of sleep apnea in ESRD. The diagnosis, epidemiology, and clinical features of sleep apnea in patients with ESRD also are considered.

Prevalence and Risk Factors of Sleep Disordered Breathing in Fabry disease: A Prospective Cohort Study

Excessive daytime sleepiness (EDS) is a frequently reported and not well-understood symptom in patients with Fabry disease (FD). Sleep-disordered breathing (SDB) is a possible factor. As deposition of glycosphingolipids in the upper airway muscles is likely, we hypothesized that obstructive sleep apnoea (OSA) is highly prevalent in FD and positively associated with its severity.All patients with FD who are followed in the Fabry cohort of the University Hospital Zurich (n = 62) were asked to participate in this prospective cohort study. Eligible patients were prospectively investigated by assessing their daytime sleepiness using the Epworth Sleepiness Scale (ESS), the severity of FD using the Mainz Severity Score Index (MSSI), and by an ambulatory overnight respiratory polygraphy between November 1, 2013, and January 31, 2015. SDB was defined as an apnea/hypopnea index (AHI) of > 5/h.Fifty-two patients (mean ± SD age 42.8 ± 14.7 years, 33% men, mean ± SD BMI 23.4 ± 3.6 kg/m) with a median (IQR) MSSI of 12 (5-19) were included. Median (IQR) ESS was 6 (2-10) and 7 patients (14%) had an ESS > 10. Thirteen patients (25%) had SDB (78% obstructive sleep apnea, 22% central sleep apnea). In the multivariable analysis, the age was the only statistically significant predictor of SDB (OR 1.11, 95% CI 1.04-1.18, P = 0.001). ESS was associated with depression (P < 0.001) but not AHI nor age.This study shows that SDB, especially obstructive sleep apnea is highly prevalent in patients with Fabry disease. However, EDS in FD seems to be related with depression rather than SDB.ClinicalTrials.gov (identifier: NCT01947634).